Primary structure of apoB-100

• Published in: Chemistry and physics of lipids Vol. 67; no. 1-3; pp. 99 - 104
• Main Authors: Yang, Chao-yuh, Gu, Zi-Wei, Yang, Manlan, Gotto, Antonio M.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Shannon Elsevier Ireland Ltd 1994; Elsevier Science
• Subjects: Analytical, structural and metabolic biochemistry; ApoB-100 primary structure; Apolipoprotein B-100; Apolipoproteins B - chemistry; Binding Sites; Biological and medical sciences; Cysteine - chemistry; Disulfide linkage of Lp[a]; Disulfides - chemistry; Free sulfhydryl of apoB on LDL; Fundamental and applied biological sciences. Psychology; Humans; Lipoprotein(a) - chemistry; Lipoproteins, LDL - chemistry; Lipoproteins, myelin; Models, Molecular; Molecular Structure; Proteins; Sulfhydryl and disulfide groups of apoB-100; Disulfide linkage of Lp[a]; ApoB-100 primary structure; Sulfhydryl and disulfide groups of apoB-100; Free sulfhydryl of apoB on LDL; Primary structure; Structural analysis
• ISSN: 0009-3084; 1873-2941
• DOI: 10.1016/0009-3084(94)90128-7

Apolipoprotein B-100 (apoB-100) is the major protein in low-density lipoprotein (LDL) and contains the ligand for binding LDL to its cell surface receptor. Lipoprotein [a] (Lp[a]) is a lipoprotein that consists of LDL and apolipoprotein [a] (apo[a]). The primary structure of apoB-100 has been determined by a combination of recombinant DNA and protein sequencing methods. Using high-performance liquid chromatographic techniques, we have identified sulfhydryl and disulfide groups of apoB-100 from LDL. Sixteen of the 25 cysteine residues in apoB-100 exist in disulfide form. All 14 cysteine residues within the N terminal end of apoB-100 are linked in disulfide bridges. Using the fluorescent sulfhydryl probe, 5-iodoacetoamidofluoresceine, two free sulfhydryls of apoB-100 on LDL were identified at positions 3734 and 4190. Based on its differential susceptibility to trypsin, apoB-100 can be divided into five domains: domain 1 (residues 1–1000), largely trypsin-releasable (TR); domain 2 (residues 1001–1700), alternating TR and trypsin non-releasable (TN); domain 3 (residues 1701–3070), largely TN; domain 4 (residues 3071–4100), mainly TR and mixed; and domain 5 (residues 4101–4536), almost exclusively TN. Based on our data, we propose that the structure of apoB-100 in LDL is probably an elongated form that wraps around the LDL particle, and that Cys 3734 of apoB-100 may be the cysteine residue linked to a cysteine of apo[a].